rewrite to inject content rather than tags

[afeld]

See opencontrol/compliance-masonry#140 (comment) for background. Basically, template tags aren't flexible enough to handle all the places we need to inject information into the document (e.g. checkboxes). We should flip the data flow so that this codebase handles inserting the data from the OpenControl files directly into the document in a single pass, rather than via an intermediate step of templatizing the Word doc for filling in later.

Acceptance criteria

• When fedramp-templater is run over an SSP docx, the Responsible Roles (at least) are inserted (rather than the tags)